Tuesday, March 26, 2024

A REVIEW OF WARDRAGON: A PORTABLE SDR KIT from https://www.rtl-sdr.com/

Over several years Aaron (@cemaxecuter) has been working on DragonOS, a popular Linux distribution that comes preinstalled with many different programs for software defined radios. A Linux distribution like this takes the hassle out of having to figure out how to compile and install various SDR programs, some of which can be quite tricky to get running. 

Recently Aaron has also been working on WarDragon, which is a set of components that he's carefully tested and put together as a ready-to-use portable SDR kit. At its core is an Airspy R2 software defined radio and x86 Mini PC that comes with DragonOS pre-installed. It also includes a USB hub and GPS dongle, as well as an HDMI dummy plug for enabling remote desktop. Everything is held together by a 3D printed frame, and enclosed in a plastic carry hard case, with the external Ethernet, USB-C, and power ports routed to the outside of the enclosure.

Aaron kindly sent us a WarDragon for an honest review. We note that we do not get to keep the WarDragon, and it will be forwarded to someone else after this review.

WarDragon Outer Enclosure
Inside WarDragon (Intel PC hidden underneath)
WarDragon with an LCD screen connected

Getting started with WarDragon is simple. Open the hard-shell case, connect an antenna to the Airspy, remove the dummy HDMI plug, connect a monitor to the HDMI port and a keyboard/mouse to a USB port, connect 12V power, and start the mini PC. A few seconds later DragonOS has booted, and you can run any of the programs pre-installed. And there are certainly a lot of programs available to play with as shown below.

List of software pre-installed in DragonOS

To get started with running it remotely we followed the instructions on the desktop to install OpenSSH, and ran the Rustdesk appimage stored in the 'post install' folder on the desktop. This allowed us to connect remotely to the unit via Rustdesk, a remote desktop interface. From there we were able to run software like SDR++, GQRX, and anything else that was preinstalled.

Aaron notes that every WarDragon will come with a free license for SDR4Space which is a command-line SDR tool for satellites. It can be used for scripting various operations, such as "recording IQ samples, predicting satellite passes and to start a record for a specific satellite and correct doppler at the same time".

The KrakenSDR software is also pre-installed on WarDragon, so the Airspy can easily be swapped out for a KrakenSDR too (or almost any other SDR as well). You can also add extra RTL-SDR units on the USB hub if desired.

Once you're done simply unplug everything and put the HDMI dummy plug back in. Close the enclosure up and you're ready to get on the move again.

One minor concern we have is that while the components are contained with the 3D printed frame, the frame itself is not held down inside the enclosure, so it can move a little during transport. Not a big deal if you are sensible about carrying it, but if you are expecting to throw the box around, something could eventually go wrong. Aaron also notes in the instructions that care should be taken to not leave WarDragon exposed to direct sunlight or in a parked car to avoid the 3D printed insert from warping. This could probably be solved by printing in a material like ABS.

Performance

The mini-PC included with WarDragon runs a 12th Generation Intel Alder Lake - N95 that can turbo up to 3.4 GHz, has 8GB of RAM, and a 256GB SSD built-in. These specs are powerful enough that the system is very snappy, software opens quickly, and software runs smoothly, even at the max 10 MHz bandwidth the Airspy supports.

These x86 mini-PCs appear to be quite a bit more powerful than their similarly priced ARM counterparts, but they do draw more power. The mini-PC running SDR++ and Airspy at 10 MHz oscillates around 20-30W of power draw, whereas a Raspberry Pi 5 running SDR++ only draws 5W.

What We'd Like to See Improved

Because the carry case is fully sealed when closed, the mini PC inside cannot be run when the case is closed, as there would be no airflow for cooling. We'd like to see some thought put into adding an external fan, and indeed Aaron has noted that in future versions he will be adding this. However, adding a fan does come at the expense of water tightness but we don't imagine many people would be throwing this in a body of water. As long as rain resistance is kept it should be alright.

We'd also like to see the SMA port brought out to the side, so an external antenna can be connected with the enclosure closed.

We can also imagine that some users might like to see a more expensive version that comes with a small screen and keyboard/mouse as part of the combo too. Aaron does note that the most common use case for operating via SSH or remote desktop via a field laptop though.

Price Review / Value

The Wardragon consists of the following components:

  • Beelink Mini PC (N95 8G+256G) - US$159 on Amazon.
  • Airspy R2 - US$169 on iTead.
  • Condition 1 11" Carry Case - US$36.99 on condition1.com
  • Other parts (cables, USB hub, USB GPS, HDMI dummy plug, outside connectors, 3D printed frame) - $US35 (estimated)
  • SDR4Space License - $US???

So that's a total of US$400 in parts (not including shipping costs) plus a bit of value from the SDR4Space license which is usually obtained on an inquiry-only basis. WarDragon currently sells for US$580. So for the extra $180, you are paying for the time to preinstall of DragonOS, drill the external mounting holes, 3D print the mount, the build time, testing time, and the ability to get support directly from Aaron himself. And we can't forget to mention the time Aaron puts into creating YouTube videos for WarDragon.

Obviously, if you are on a tight budget it would make sense to try and build your own system. But overall we think WarDragon is not a bad deal if your time is worth more and you just want a portable system to get up and running with DragonOS ASAP.

 

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Economics Humor by Dan Mitchell

I shared four columns of economics humor in 2023 (March, August, November, and December), so we’re due for our first 2024 installment.

Let’s start with an example that easily could be part of socialism humor or communism humor, but it seems to apply to any strain of leftism.

Next, I’ve repeatedly debunked the silly idea that there is pervasive wage discrimination, but all of the research in that field of labor economics is based on the assumption that there are two genders.

The woke crowd is going to have to update their assumptions.

Next, I found a very appropriate motto for California government.

Our fourth item is the government version of the Field of Dreams.

Per tradition, I’ve saved the best for last.

I’ve written many serious columns about the failure and absurdity of anti-money laundering laws. Basically, politicians have created a system where banks and other financial institutions are compelled to spy on customers (supposedly to fight crime, but such policies are utterly ineffective).

Anyhow, the Australian government decided to expand these AML laws and rules by requiring banks to ask customers to justify large bank withdrawals. So this clever fellow recorded some amusing reasons.

You may not think money-laundering policy lends itself to humor, but there’s also an amusing anecdote involving a former President.

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Everything You Need to Know for Last-Minute Eclipse Travel by Laura Falin

 

In just a few weeks, parts of the South, Midwest, and Northeast will be in the path of totality for a 2024 solar eclipse. Although the event is just a few weeks away, there is still time to plan a trip to witness this celestial event. RVshare has a trove of eclipse travel articles and information. This particular article will share everything you need to know for last-minute eclipse travel. We’ll show you where to visit, how to find accommodations, and what you’ll want to bring with you for this exciting event.

This post contains affiliate links. RVshare may receive compensation if you make a purchase after clicking on a product or service link.

Where and When it Will Happen

an eclipse map to help people plan last-minute eclipse travel

The solar eclipse begins in the U.S. at 2:27 pm EDT in Texas and ends at 3:34 pm EDT in Maine. The area where the eclipse will be complete – known as the path of totality – makes a wide arc through the South and up to the Northeast, hitting the cities of Dallas, Texas, Little Rock, Arkansas, Cleveland, Ohio, Erie, Pennsylvania, Buffalo, New York, and Burlington, Vermont.

This eclipse is expected to draw large crowds, partly because the path of totality goes through many big cities and urban areas. In fact, cities like Buffalo could almost double in size thanks to eclipse tourists.

How to Find Accommodations

It’s true that a lot of hotels and campgrounds have been booked for months, if not a year, in advance. But take heart – there are still places to find last-minute rooms or places to camp. Here are a few tips for finding a place to stay in the path of totality.

1. Expedia Eclipse Page

If you’re looking for hotels, Expedia has an eclipse page to help you locate some near the path of totality. Many of the hotel listings will give you a distance in miles from the eclipse to help you with your planning. At this stage, you’ll want to be flexible. Consider staying a little farther away or loosening your requirements for a room to broaden your search range.

2. Finding a Campground

You may have better luck finding a campground than a hotel room at this point. Hipcamp has a listing of the best camping spots along the path of totality and some of them still have availability at the time of the eclipse. There are also lots of state parks in the path of totality where you can camp. As you look for campgrounds, you may also have better luck searching farther north where the weather is colder (if you’re able to camp in chilly conditions).

3. Options if Campgrounds Are Booked

If you don’t want to stay in a traditional campground, or you find that a lot of the ones you like are booked, there are several other camping options as well. Although Bureau of Land Management lands are often a popular spot for dispersed camping, there aren’t any near the path of totality. However, there are some other options:

  • National Forest dispersed camping
  • National Forest campgrounds
  • State Forest dispersed camping
  • Land maintained by the state Department of Fish and Wildlife or the Department of Natural Resources
  • Army Corps of Engineers campsites

4. RVshare Rentals

RVing is an excellent way to experience the eclipse. You can set up your rig in the path of totality several days beforehand and you won’t have to drive at all for the big event. It’s easier to bring along comfortable chairs, telescopes, blankets, and other equipment you want for your viewing without having to worry about carting that stuff on a plane. You’ll also have a bathroom and other conveniences at hand all day long, as opposed to people who drive to a park to watch the event.

If you choose to camp in a colder location, an RV or trailer will also provide you with warmth and a comfortable place to prepare and eat meals.

RV rentals can also be less expensive than paying to stay in a hotel.

A quick check of RVshare rentals along the path of totality shows that there are still options left if you’re looking to rent one. If you’re having trouble finding one, consider renting an RV outside of the path of totality and driving to your destination.

5. Premium Campground & Rental Packages

You can skip the hassle of finding both a campground and an RV rental by booking one combo package that takes care of everything! Spot2Nite and RVshare have paired up to provide all-inclusive rentals for the eclipse. Customers get a campground reservation along the eclipse viewing path, plus a fully equipped travel trailer to use. The trailer is delivered, set up, and picked up after the eclipse – all you do is show up and enjoy your stay.

Eclipse Events

Of course you’re traveling to witness the eclipse itself on April 8. But many towns and communities are hosting eclipse events in the days and hours leading up to the Big Event. RVshare has compiled a database of events in Texas, Oklahoma, Arkansas, Illinois, Pennsylvania, and other areas along the path of totality. Some of the happenings begin as early as April 4th, and while most culminate with the eclipse itself, some events wrap up on April 9th.

You’ll find everything from music festivals to astronomy gatherings to family-friendly activities. There are options for the entire family.

National parks across the country – even those not in the path of totality – are hosting events celebrating the eclipse as well. You can find their offerings on their website. Simply click the April 8 date on the calendar to see what each of the parks has planned.

NASA also has a variety of eclipse-related presentations and celebrations planned. You can find NASA’s plans on their website.

Eclipse Tips

Now that you have your accommodations squared away, and some plans to enjoy eclipse events, make sure you’re prepared for the event itself!

1. Don’t Forget Eclipse Equipment

Grab some eclipse glasses ahead of time so you can safely watch the sun disappear. You may also want a solar filter sheet to view the eclipse through a telescope, binoculars, or camera.

Don’t forget items to make the rest of your stay enjoyable as well! You’ll want comfy camp chairs to sit in while you wait for the Big Event. You may also want a cozy blanket or pillows. Card games or books can help pass the time while you wait. Some people may want a travel journal where they can write memories and save mementos from the trip.

2. Plan for Eclipse Traffic

Many towns are planning for a much higher traffic volume than usual – another reason why RV camping is an excellent idea! You may encounter eclipse traffic the weekend before the event, the day of the eclipse, and the day after as everyone heads home. If you’re driving to a location on the day of the eclipse, make sure to give yourself plenty of time in case the roads are busy. And if you’re driving in a few days before (good idea!), load up some road trip podcasts and be ready to encounter some fellow eclipse enthusiasts doing the same thing.

3. Be Ready for the Weather

If you’re camping in the south, you should experience pleasant weather in early April. However, the farther north you venture, the bigger the likelihood of a spring storm. Some areas are still getting snow at that time of year. Make sure your RV can handle cold temperatures if you plan to camp. You may also want a few backup ideas in case the area where you are staying is cloudy. Check the weather forecast ahead of time, and see if you can plan where to be for clear skies.

Of course, weather is ultimately beyond anyone’s control. If you can plan a fun RV camping trip where everyone enjoys themselves, you’ll be less

4. Get Some First-Hand Advice

RVshare blog contributors Happy Trails Family camped out to witness the 2017 total eclipse. They have some great advice for families hoping to camp and enjoy the 2024 eclipse next month. It’s helpful to get tips from a family that has already tried this adventure.

If you’re hoping to experience the April eclipse but haven’t booked your experience yet, you still have a good chance of finding accommodations and supplies to enjoy the event. Good luck and enjoy chasing the sun…and the shadows as well!

THE POTA BABE AND AX1 MAKE by TERI KO4WFP

 Sunday, March 10th, my son had another Dungeons & Dragons session. I figured why not play QRP radio again on the north end of Skidaway Island at the University of Georgia Skidaway Institute of Oceanography. The weather appeared more conducive for radio than my previous visit. My friend Glenn W4YES accompanied me.

Skidaway Island’s Location in Savannah, GA area from Google Maps
UGA Institute of Oceanography at north end of island as per Google Maps

I chose as my location the bluff behind the aquarium which contains picnic tables and looks out over the intracoastal waterway. There was a stiff breeze but what a pretty place to play radio!

My QTH on the bluff

The Straight Key Century Club (SKCC) was holding the Weekend Sprintathon (WES), a monthly event for members. As I mentioned in my previous Skidaway article, SKCC is an organization with 28,000 plus members that use mechanical keys (straight, cootie, and bug) for their QSOs. Participating in their sprints is a simple way (like POTA) for new ops to gain experience and build confidence.

I figured I’d accomplish several things at once today: get more QRP experience with something other than POTA, garner a few more QSOs on my march toward Senator for SKCC, and use the AX1.

In researching my upcoming summer POTA trip, I read a post by Bob Condor (K4RLC) on the W4SOTA groups.io about modifications to the AX1. I plan to attempt my first SOTA activations during the trip and want light, nimble antenna options.

Admittedly, the AX1 and I haven’t been on the best terms. Bob modified his by adding three 14’ radials instead of the counterpoises with which the antenna comes.  He used this configuration during a trip to Greece and had good results. I figured, why not give it a try? It was easy to make the radials with a lug connector on each end to add them to the AX1 mount on my Joby Gorillapod (the only tripod I currently have).

While Glenn took a leisurely walk on the nature trail at the bluff, I began on 20 meters.

I engaged the ATU which dropped the SWR from 2.2 down to 1. There were a lot of stations on 20 meters but I finally found a place to settle. After 8 minutes calling CQ, Randy K8ZAA answered me and gave me a 579 in MI, a good signal report for the AX1.

Given the paucity of stations answering my CQ, I decided to move to 17 meters but realized the WARC bands are not allowed in the SKCC WES so I opted for 15 meters instead. After a few minutes calling CQ, Bob AF5Z answered me. He gave me a 449 in Texas.

It became quiet again after that QSO so I jumped to 40 meters, had no callers, and moved back to 20 meters. After 10 minutes calling CQ, Jerry WA4JK answered me and gave me a 559 in Alabama. By this point, the wind had increased and Glenn and I had enough of being buffeted by what felt like gale-force winds. However, I still had an hour and a half before my son’s Dungeons & Dragons session ended so this POTA Babe wasn’t ready to call it quits.

We packed up and relocated to the field in which I set up last time, it offering less windy conditions.

We set up the AX1 again, this time on top of the car draping the radials over the front and both sides. I called CQ on 14.043 and Steve NQ8T kindly answered my call. From Ohio, he gave me a 559.

Okay. Time for me to stop “trash talking” the AX1 because it was performing just fine today. Oh, by the way, Steve was running 1 watt and I gave him a 559 for his RST. QRP-2-QRP is fun!

SKCC QSO Map at Skidaway Island 3-10-24 http://tools.adventureradio.de/analyzer/

At this point, it was time to call QRT and pick up my son.

Overall, the outing was a success in my book. Of the four SKCC QSOs I had, three helped me with my progress toward Senator. I now stood at 61 out of 200 contacts needed to reach that rank.  I had also deployed the AX1 and was pleased with its performance.

The one “fly in the ointment” for this outing was my key. I used the CW Morse SP4 (my portable key), changing the KX2 CW key settings to “hand” to make it a mechanical key. When I sent with the key, sometimes the key sounded like it was bouncing which distorted my characters. I didn’t have another key I could use as a mechanical key with me so I made do with it as best I could. (Thank you to those who contacted me for their patience with my unusual fist.)

Later that evening, Glenn figured out one of the paddles is twisting slightly. The movement doesn’t affect the characters when I use the SP4 in iambic mode but it certainly showed when being used a cootie. What is also strange is I can use the SP4 as a cootie with my Yaesu FT-891 using a mono plug to make it mechanical and it sends flawlessly – no extra dits or scratchy sounding code.

I could bring my CW Morse camelback key (a straight key) for any portable SKCC work, but I’d prefer a cootie which is my favorite key. So I’ll open it up to y’all to suggest a cootie for QRP portable work that is actually a cootie and not a paddle jimmy-rigged into being a cootie.

See everyone next time when I head out for some radio therapy.  As I often say, stay tuned…

Equipment Used

[Note: All Amazon, CW Morse, ABR, Chelegance, eBay, and Radioddity links are affiliate links that support QRPer.com at no cost to you.]

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Friday, March 22, 2024

How to Test Coaxial Cable Posted by Mark Haverstock, K8MSH

Coax became popular with hams after World War II when war surplus was plentiful. Hams liked it because it was easy to obtain, relatively inexpensive, and easy to install—much easier than ladder line.

We’ve all got some. Whether it’s for cable TV, satellite, Internet, or ham radio, coaxial cable has become the RF highway for moving signals from one point to another. Fortunately, there are no orange barrels or detours—most of the time. But there are occasions when we need to check, repair, or even replace coax.

DVM Checkup

Materials NeededDigital voltmeter, jumper with alligator clips and/or SO-239 shorting adapter, dummy load (optional)

The most common and readily available test tool is the digital voltmeter (DVM). Cheaper ones include the basics: voltage, current, continuity, resistance. The more expensive ones add features like capacitance, frequency, amperage, and others. All you need for this checkup are the continuity and resistance settings.

To enter continuity mode, turn the dial to the continuity symbol, which will resemble sound waves or a symbol for a musical note. If you’re using an auto ranging multimeter, you may need to press the “mode” or “select” button a few times until the symbol also appears on your screen.

For testing unconnected patch cords or rolls of coax, touch the multimeter probes on both sides of the cable. Check the shield ends, then the center conductor—if it’s bulk coax without connectors you’ll need to strip the end. If you don’t hear a loud beep, it means there’s a break in the wire or a faulty coax connector.

Stress points on the cable near an antenna rotor or a tight bend can cause the conductor to break, especially with solid wire. Sloppy soldering, or corrosion, on connectors can cause poor connections and problems with your antenna system.

If the cable is already installed, make sure to disconnect it from your radio and antenna—below any matching devices. Things like baluns, ununs, and chokes can cause false readings. For example, a 4:1 balun can read as a DC short on a DVM but operate properly at radio frequencies.

It’s a pain to check a 100-foot coax run that’s already in place—the meter test leads aren’t long enough. Instead, check the cable for an existing short by touching one probe to the center pin and one to the outside of the PL-259 connector at one of the ends. If there’s no beep indicating a short, make it a single conductor by tying together one end, connecting the center pin and outside of connector. The alligator clip jumper will work, but I prefer using a panel mount SO-239 with the center grounded to the pin.

Touch both leads at the remaining end with the DVM leads. If you hear the beep, both shield and center conductor are okay. If not, check your connectors for issues or consider replacing the entire run.

Some prefer to use a similar method with the resistance scale and a 50-ohm dummy load, which substitutes for your antenna. No dummy load? You can use a 47-ohm resistor, which is close enough. When you touch the leads, the 0L reading should change to something in the ballpark of 50 ohms if the coax is okay.

In the next section, you’ll see how to check the cable’s integrity. Sections of the coax you replaced could test okay and possibly be recycled to make jumpers or short runs.

Antenna Analyzer

Materials Needed: Antenna analyzercoax connector or alligator clip jumper to short the end of cable, velocity factor (VF) numbers for cable(s) you’re testingVelocity factor can be found at the dealer or manufacturer website.

Most hams use antenna analyzers while building and tuning antennas, but it has other features that will help you measure coax length without a tape measure, calculate loss in dB, and discover its general condition. The examples that follow are based on one popular model, the RigExpert AA-55Zoom, measuring DX Engineering RG-8X 50-ohm Coaxial Cable (DXE-8X). Consult your specific analyzer’s instructions for operation. 

Coax Length

Got some coax but no tape measure? Let your antenna analyzer do the work. On the AA-55, select TOOLS from the menu, then LENGTH & VF. Enter the velocity factor and press OK. Length will appear on the screen in the format you’ve selected (feet or meters).

You can also find velocity factor by entering a known length. The photo below shows the length of a patch cable I randomly selected, calculated by the AA-55.

Loss

The greater the length of coax cable you use, the more signal loss you will have. This is due to a number of factors. Losses within the coax cable itself come from the resistance of the conductors. Dielectric loss represents another of the major losses in most coax cables—the dielectric is the insulation around the center conductor. The loss increases with frequency.

Radiated loss of a coax cable is normally much less than the resistive and dielectric losses. But some very cheap coax cables may have a very poor outer braid, and in these cases will contribute to additional losses.

To find how much attenuation there is in a length of cable, go to the TOOLS MENU and choose CABLE LOSS. You’ll take two measurements, the first with the cable end open and the second with the end shorted. The AA-55 will collect the data and show a graph (below) of the losses in dB. You can change the frequency by moving the left/right arrows.

The loss graph shows 1.46 dB attenuation for the 150-foot test cable at 7.150 MHz, which has seen plenty of action at Field Days and Ohio State Parks on the Air (OSPOTA) activations.

Cable Impedance vs. Frequency

To find the impedance in a length of cable, go to the TOOLS MENU and choose CABLE IMPEDANCE. You’ll take two measurements, the first with the cable end open and the second with the end shorted. The AA-55 will collect the data from 100KHz to the maximum frequency on your analyzer and show a graph (below) of the impedance at any given frequency. You can change the frequency by moving the left/right arrows. You’ll notice in this case, it’s very close to the 50-ohm specs.

This can help you identify unmarked coax as well as check compliance with the coax specs provided by the manufacturer. It’s also a way to monitor coax condition from season to season. As the sun bakes our coax installed outdoors, impedance and losses will change over time due to exposure.

The Inside Story

It’s not practical to peel back the jacket and shield to examine a length of coax—it would render the cable useless. But tools like the DVM and antenna analyzer will let you check and assess the viability of your coaxial cable electronically to help you make decisions about repairing or replacing.